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Wave Speed, Frequency, and Wavelength in the Spectrum
All electromagnetic waves in vacuum travel at c = 3.0 × 10⁸ m/s.
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Wave Speed, Frequency, and Wavelength in the Spectrum
Recommended for Class 10
Wave Speed, Frequency, and Wavelength in the Spectrum
All electromagnetic waves in vacuum travel at:
**c = 3.0 × 10⁸ m/s**
The wave equation is:
**c = fλ**
Frequency and Wavelength
Because `c` is constant in vacuum:
**f ∝ 1λ**
If frequency increases, wavelength decreases.
Example
For an electromagnetic wave with:
`f = 1.0 × 10⁸ Hz`
then:
`λ = cf`
`λ = 3.0 × 10⁸ / 1.0 × 10⁸`
**λ = 3.0 m**
In Materials
Electromagnetic waves generally travel more slowly in materials than in vacuum.
When entering a new medium:
frequency remains unchanged
but:
speed and wavelength may change
Wave Speed, Frequency, and Wavelength in the Spectrum — Advanced
Common Mistakes
Common Mistakes
- Mistake
Do not use 340 m/s; that is approximately the speed of sound in air.
- Mistake
Do not change frequency at a boundary unless the source frequency itself changes.
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Practice
PQ
Q1. State c.
PQ
Q2. Write c=fλ.
PQ
Q3. Calculate λ for a given f.
PQ
Q4. Explain boundary frequency behaviour.
PQ
Q5. Compare vacuum and material speeds.
Exam Practice
EQ
Q1. State c.
EQ
Q2. Write c=fλ.
EQ
Q3. Calculate λ for a given f.
EQ
Q4. Explain boundary frequency behaviour.
EQ
Q5. Compare vacuum and material speeds.
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.